It is well known in the oil and gas drilling industry to equip the upper end of the surface pipe of an oil or gas well with blowout preventer devices to prevent fluid and gases from being blown out of the well in the event a high pressure zone is encountered while drilling. One type of blowout preventer contains fluids and/or gases which would escape through the annulus between the well bore wall and the drill pipe. Another type of blowout preventer contains fluids and/or gases which would escape through the central passage of the drill pipe. These latter types of blowout preventers are known as inside or internal blowout preventers (IBOP's).
The most common IBOP's take the form of a blowout sub which includes a tubular housing containing a valve to control the passage of gas or fluids and threaded ends such that the blowout sub may engage the upset end of a drill pipe on one end and on the other end another threaded member such as the drive sub of a top drive. FIG. 1 illustrates a conventional pipe handling apparatus (“pipe handler”) 100 such as the Varco PH-85 provided by Varco International of Houston, Tex. and a top drive assembly 101 having an IBOP sub 104 attached thereto. It will be understood that only particularly relevant elements of pipe handler 100 are shown schematically in the Figures since pipe handler 100 does not form part of the present invention. Top drive assembly 101 includes a drive head 120 having the drive motor, drive gearing, and the threaded drive sub 103 which transmits power from the motor to the lower elements of the drill string. The lifting or lowing of drive head 120 and the following string elements is carried out by a conventional hook and traveling block arrangement 102 and drive head 120 is maintained in alignment over the well bore by a drive head dolly 112 moving along top drive guide rail 111. Pipe handler 100 will include a pipe handler frame 109 whose vertical position relative to drive head 120 may be adjusted with pipe handler lift cylinder 113. Pipe handler frame 109 includes internally splined torque tube 108 and clamp cylinder assembly 110. Although not explicitly shown in FIG. 1, those skilled in the art will understand that torque tube 108 will be connected to a torque generating means such that torque tube 108 can impart torque to elements of the drill string as described below. Likewise, it will be understood that clamp cylinder assembly 110 is constructed such that it can grip a string element and hold it stationary against the torque generated by torque tube 108.
The IBOP sub 104 seen in FIG. 1 includes an upper IBOP valve 105 threaded to drive sub 103 at connection 125a, lower IBOP valve 107 threaded to upper IBOP valve 105 at connection 125b, and sub-saver connector end 113 threaded to lower IBOP valve 107 at connection 125c. Typically upper IBOP valve 105 is the primary IBOP valve and may be remotely controlled while lower IBOP valve 107 is a manually opened and closed secondary valve used as a backup to upper IBOP valve 105. Upper IBOP valve 105 also differs from lower IBOP valve 107 in that IBOP valve 105 has a series of splines 106 on its external surface. To help illustrate the environment in which pipe handler 100 and blowout sub 104 are employed, FIG. 1 also illustrates a drill deck or rig floor 118 having a conventional rotary table 117 position therein. Rotary table 117 includes a conventional manual slip assembly 114 which maintains the vertical position of drill pipe 116 (and the drill string below it) when drill pipe 116 is not engaging sub saver 113 and capable of being supported by hook and traveling block assembly 102.
When it is desired to make up or break out the connection between a section of drill pipe 116 and sub saver 113 (i.e. connection 125d), pipe handler 100 is moved into the position seen in FIG. 2. Clamp cylinder assembly 110 grips the top joint end of drill pipe 116 while splined torque tube 108 engages the external splines 106 on upper IBOP valve 105. It will be understood that connections 125a, 125b, and 125c are made up at higher torque values than connection 125d. Thus, when torque tube 108 applies torque to splines 105 while clamp cylinder assembly 110 holds pipe 116 stationary, connection 125d may be made up or broken out. Moreover, connection 125a is made up to a higher torque value than any of connections 125b-125d in order to ensure that connection 125a is not inadvertently broken. As a further precaution in certain drilling operations (such as those employing the IBOP's illustrated in the figures), the torque to which connection 125a is made up will be greater than the torque which can be generated by drive head 120.
Since connection 125a is made up to a torque value higher than connections 125b-125d and it may not be possible to break out connection 125a with the torque generated by drive head 120, the prior art practice was typically to have a person breakout joint 125a and upper IBOP valve 105 using some type of large manual wrench, a/k/a “rig tongs.” It is also typical that connection 125a will be at an elevated position above the rig floor, requiring the worker breaking out connection 125a to mount a step ladder or some type of elevated structure to properly access connection 125a. This present procedure both causes unacceptable delays in expensive drilling operations and presents fall and other injury hazards for workers. What is needed in the art is a tool overcoming the disadvantages which exist in the current procedure for breaking out or making up connections such as found in IBOP sub assemblies.